Child resistant tamper proof container-closure assemblies are not new per se. For example, in U.S. Pat. No. 3,888,376 entitled SAFETY CLOSURE CAP FOR CONTAINERS, the cap has a depending skirt having internal spiral threads which cooperate with threads on the bottle finish to permit application and removal of the cap. The threads have inter-engaging shoulders which permit rotation of the cap to apply it to the container and interengage to normally lock the container against rotation in a direction to remove it. The cap has a resilient liner so that when it is desired to remove the cap, the user applies a downward force against the top compressing the resilient liner and moving the cap axially downwardly on the neck to displace the interengaging shoulders and permit turning of the cap in a direction to remove it.
The safety closure shown in the Cook, U.S. Pat. No. 3,952,899 issued Apr. 27, 1976 and entitled SAFETY CLOSURE CAP shows a similar arrangement utilizing a compressible liner on the inside of the top of the cap for the cap biasing force.
The Wiles, et al U.S. Pat. No. 4,387,817 issued Jun. 14, 1983, and entitled CHILD RESISTANT CONTAINER COVER also shows a child resistant tamper evident container-closure. There are a series of circumferentially equi-spaced harpoon shaped threads each having an arrow head portion generally parallel to the center line of the closure and designed to interlock with a series of spiral thread portions on the bottle finish when the cap is threaded to apply it to the container. The arrow head portion 11 locks with the threads in the manner shown in FIG. 2 and much like the Cook assemblies discussed above, can be disengaged by pressing the cap axially downwardly against the bias of a liner made of a suitable resilient material.
The child resistant closure assembly shown in the Steiner, U.S. Pat. No. 4,522,307 issued Jun. 11, 1985 entitled CHILD RESISTANT TAMPER EVIDENT CLOSURE comprises an outer closure shell having an integral tamper evident band encircling and attached to the lower edge of the closure cap skirt and an inner shell having threads for engaging the container threads and including a sealing gasket. Cooperating rachet means are provided on the inner and outer shells which need to be engaged to turn the outer shell in a direction for removal of the inner shell from the container. The tamper evident band which includes a downwardly extending projection prevents this movement so that the band must be either removed prior to closure removal or it will be automatically torn loose as a result of the necessary squeezing action for removal. In either case tearing of the band indicates that an attempt was made to remove the cap. This provides a visual means for determining whether there has been any tampering of the cap seal.
In the Montgomery U.S. Pat. No. 4,682,700 for SAFETY CLOSURE AND CONTAINER PACKAGE, the bottle finish and skirt of the container cap have complementary screw threads. The cap has an inwardly directed circumferentially extending retention bead 28 which on application of the cap over the container retention bead 28 slips axially downward on upper flange surface 38 and is gradually expanded as it approaches the flange apex. Continued rotation compresses gasket 18 between the cap top 20 and lip 42 at the end of the container neck 30. Now when the cap is rotated in a retrograde direction, cap retention bead is forced against the abrupt lower flange surface 40 to resist removal. Enough turning torque must be applied to stretch the cap bead over the apex 36 of the flange which is difficult for children to do and thus provides a tamper resistant feature.
The remaining references listed below are of interest to the extent that they show various cap and container arrangements having a child resistant feature.
Even though the container closure assemblies discussed above are generally suitable for the purposes intended, it has been found that they all share certain disadvantages and drawbacks. For example, it has been found that over a period of use, the liner tends to lose some of its resiliency and this unfavorably impacts the child resistant feature of these assemblies. Furthermore, a number of the embodiments are rather complicated and expensive to manufacture.
KingCONTAINER AND CLOSURE4,084,717B. WeigandCONTAINER CLOSURE3,339,770Gach, et al.SAFETY CLOSURE3,770,153CookeSAFETY CLOSURE CAP4,139,112BialobrzeskiCONTAINER SAFETY CLOSURE4,153,172Brozell et al.CHILD-RESISTANT CLOSURE ANDUS/2003/0121877CONTAINER PACKAGEThompsonCONTAINER AND CAP4,856,667KuszCHILD RESISTANT PACKAGE5,711,442